Distance-measuring device of measuring distance according to variation of imaging location and calibrating method thereof

ABSTRACT

A distance-measuring device is utilized for measuring a measured distance between a measured object and the distance-measuring device. The distance-measuring device reduces the effect of a background light and a flicking light by removing the part corresponding to the background light and the flicking light from light-sensed signals generated by an image sensor of the distance-measuring device. In addition, the distance-measuring device calculates a calibrating parameter for calibrating an assemble-error angle of the distance-measuring device, according to an imaging location of a reflective light obtained by measuring a calibrating object with a predetermined distance. In this way, the distance-measuring device can correctly calculate out the measured distance.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a distance-measuring device, and moreparticularly, to a distance-measuring device of measuring distanceaccording to variation of imaging location.

2. Description of the Prior Art

In the prior art, the distance-measuring device emits a detecting lightto a measured object, and receives a reflecting light generated by themeasured object reflecting the detecting light. The distance-measuringdevice calculates the distance between the measured object and thedistance-measuring device according to the variation of the imaginglocation of the reflecting light. However, when the distance-measuringdevice senses the reflecting light from the measured object, thedistance-measuring device is affected by the background light and theflicker phenomenon (for instance, the flicker of the fluorescent lampcaused by the frequency of the AC power supply) at the same time. Hence,the distance-measuring device calculates an incorrect measured distancebecause of the above-mentioned reason. Moreover, since the locations ofthe components of the distance-measuring device may shift or rotate dueto the assembling error during the fabrication, the accuracy of themeasured distance obtained by the distance-measuring device is furtherdeteriorated, causing a great inconvenience.

SUMMARY OF THE INVENTION

The present invention provides a distance-measuring device of measuringdistance according to variation of imaging location. Thedistance-measuring device has a lighting component, a first lens, and animage sensor. The lighting component is utilized for emitting adetecting light to a measured object for the measured object generatinga reflecting light. The first lens is utilized for focusing a backgroundlight or the reflecting light. The image sensor is utilized for sensingan energy of a light focused by the first lens so as to generate Mlight-sensed signals. The distance-measuring device comprises alighting/sensing controlling circuit, and a distance-calculatingcircuit. The lighting/sensing controlling circuit is utilized forcontrolling the lighting component to emit the detecting light andcontrolling the image sensor to sense the energy of the light focused bythe first lens at the same time during a distance-sensing phase, so thatthe image sensor generates M first light-sensed signals, and forcontrolling the lighting component not to emit the detecting light andcontrolling the image sensor to sense the energy of the light focused bythe first lens at the same time during a noise-sensing phase, so thatthe image sensor generates M second light-sensed signals. M represents apositive integer. The distance-calculating circuit is utilized fordetermining an imaging location of the reflecting light on the imagesensor according to the M first light-sensed signals and the M secondlight-sensed signals, and calculating a measured distance between thedistance-measuring device and the measured object according to theimaging location, a focus length of the first lens, and a predetermineddistance between the lighting component and the image sensor.

The present invention further provides a calibrating method. Thecalibrating method is utilized for calibrating a distance-measuringdevice of measuring distance according to variation of imaging location.A lighting component of the distance-measuring device emits a detectinglight to a measured object. The measured object reflects the detectinglight to an image sensor of the distance-measuring device for imaging ata first imaging location. The distance-measuring device calculates ameasured distance between the measured object and the distance-measuringdevice according to the first imaging location, a focus length of afirst lens of the distance-measuring device, and a predetermineddistance between the lighting component and the image sensor. Thecalibrating method comprises the lighting component of thedistance-measuring device emitting the detecting light to a calibratingobject, and the calibrating object reflecting the detecting light to theimage sensor of the distance-measuring device for imaging at a secondimaging location, calculating out a calibrating parameter forcalibrating an assembling-error angle according to a known distance andthe second imaging location, and the distance-measuring devicecalculating out the calibrated measured distance according to thecalibrating parameter. A distance between the distance-measuring deviceand the calibrating object is the known distance.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 and FIG. 2 are diagrams illustrating the structure and theoperation principle of a distance-measuring device according to thepresent invention.

FIG. 3 is a diagram illustrating the operation principle of thedistance-measuring device reducing the flicker phenomenon according tothe present invention.

FIG. 4 is a diagram illustrating a calibrating method of calibrating thelighting-error angle of the detecting light emitted by thelighting-component.

FIG. 5 and FIG. 6 are diagrams illustrating a calibrating method ofcalibrating sensing-error angles rotated by the image sensor because ofthe assembling error.

FIG. 7 is a diagram illustrating the structure of an image sensoraccording to a first embodiment of the present invention.

FIG. 8 is a diagram illustrating the operation principle of detectingthe imaging location of the reflecting light by the image sensor of FIG.7.

FIG. 9 is a diagram illustrating the structure of an image sensoraccording to another embodiment of the present invention.

FIG. 10 is a diagram illustrating the operation principle of detectingthe imaging location of the reflecting light by the image sensor of FIG.9.

FIG. 11 is a diagram illustrating the structure of an image sensoraccording to another embodiment of the present invention.

DETAILED DESCRIPTION

The present invention provides a distance-measuring device of measuringdistance according to the variation of the imaging location. Thedistance-measuring device of the present invention reduces the effect ofthe background light and the flicker phenomenon by removing the parts ofbackground light and the flicking light from the light-sensed signalsgenerated by the image sensor. In addition, the present inventionfurther provides a calibrating method for calibrating the assemblingerror of the distance-measuring device, so as to improve the accuracy ofmeasuring the distance.

Please refer to FIG. 1 and FIG. 2. FIG. 1 and FIG. 2 are diagramsillustrating the structure and the operation principle of adistance-measuring device 100 according to the present invention. Thedistance-measuring device 100 measures distance according to thevariation of the imaging location. More particularly, thedistance-measuring device 100 measures the measured distance D_(M)between the measured object MO and the distance-measuring device 100.The distance-measuring device 100 comprises a lighting/sensingcontrolling circuit 110, a lighting component 120, an image sensor 130,a distance-calculating circuit 140, a parameter-calculating circuit 150,and a lens LEN₁. The coupling relations between the components of thedistance-measuring device 100 are shown in FIG. 1, and hence will not berepeated again for brevity.

The lighting/sensing controlling circuit 110 generates a lighting pulsesignal S_(LD), a shutter pulse signal S_(ST), a phase signal S_(P), areading signal S_(RE), and a known-distance signal S_(D). Measuring thedistance by the distance-measuring device 100 can be divided into twophases: 1. distance-sensing phase; 2. noise-sensing phase. During thedistance-sensing phase, the lighting/sensing controlling circuit 110generates the lighting pulse signal S_(LD) representing “lighting” andthe shutter pulse signal S_(ST) representing “turning-on”, wherein thepulse widths of the lighting pulse signal S_(LD) representing “lighting”and the shutter pulse signal S_(ST) representing “turning-on” are bothequal to T_(C). Then the lighting/sensing controlling circuit 110generates the reading signal S_(RE) representing “reading” and the phasesignal S_(P) representing “sum”, wherein the pulse widths of the readingsignal S_(RE) representing “reading” and the phase signal S_(P)representing “sum” are both equal to T_(R). During the noise-sensingphase, the lighting/sensing controlling circuit 110 generates theshutter pulse signal S_(ST) representing “turning-on” and the lightingpulse signal S_(LD) represents “not-lighting” at the time, wherein thepulse width of the shutter pulse signal S_(ST) representing “turning-on”during the noise-sensing phase is still equal to T_(C). Then thelighting/sensing controlling circuit 110 generates the reading signalrepresenting “reading” and the phase signal S_(P) representing “noise”,wherein the pulse widths of the reading signal S_(RE) representing“reading” and the phase signal S_(P) representing “noise” are still bothequal to T_(R).

The lighting component 120, according to the lighting pulse signalS_(LD), emits a detecting light L_(ID) to the measured object MO, sothat the measured object MO generates a reflecting light L_(RD). Moreparticularly, when the lighting pulse signal S_(LD) represents“lighting”, the lighting component 120 emits the detecting light L_(ID)to the measured object MO; when the lighting pulse signal S_(LD)represents “not-lighting”, the lighting component 120 does not emit thedetecting light L_(ID). In addition, the lighting component 120 can be aLight-Emitting Diode (LED) or a laser diode. When the lighting component120 is an LED, the distance-measuring device 100 selectively comprises alens LEN₂ for focusing the detecting light L_(ID) emitting to themeasured object MO.

The lens LEN₁ focuses a background light L_(B) or the reflecting lightL_(RD) to the image sensor 130. The image sensor 130 comprises M sensingunits CS₁˜CS_(M). In the present embodiment, the M sensing unitsCS₁˜CS_(M) are illustrated to be arranged side by side for example. Thewidth of each sensing unit is equal to a pixel width W_(PIX). That is,the total width of the M sensing units CS₁˜CS_(M) arranged side by sideis equal to (M×W_(PIX)). The sensing units CS₁˜CS_(M) sense the energyof the light focused by the lens LEN₁ according to the shutter pulsesignal S_(ST). More particularly, when the shutter pulse signal S_(ST)represents “turning-on”, the sensing units CS₁˜CS_(M) sense the energyof the light (for example, the background light L_(B) or the reflectinglight L_(RD)) focused by the lens LEN₁ so as to generate thelight-sensed signal; when the shutter pulse signal S_(ST) represents“turning-off”, the sensing units CS₁˜CS_(M) do not sense the energy ofthe light focused by the lens LEN₁. For example, when the shutter pulsesignal S_(ST) represents “turning-on”, the sensing unit CS₁ senses theenergy of the light focused by the lens LEN₁ so as to generate thelight-sensed signal S_(LS1), the sensing unit CS₂ senses the energy ofthe light focused by the lens LEN₁ so as to generate the light-sensedsignal S_(LS2), . . . , and the sensing unit CS_(M) senses the energy ofthe light focused by the lens LEN₁ so as to generate the light-sensedsignal S_(LSM). In addition, when the reading signal S_(RE) represents“reading”, the sensing units CS₁˜CS_(M) outputs the light-sensed signalS_(LS1)˜S_(LSM), respectively.

The distance-calculating circuit 140 comprises a plurality of storingunits for respectively storing the light-sensed signals S_(LS1)˜S_(LSM)outputted by the sensing units CS₁˜CS_(M). The distance-calculatingcircuit 140 sets the attributes of the received light-sensed signalsaccording to the phase signal S_(P). In the present embodiment, thedistance-calculating circuit 140 is illustrated to comprise M storingunits M₁˜M_(M) for example. When the phase signal S_(P) represents“sum”, the storing units M₁˜M_(M) set the attributes of the receivedlight-sensed signals positive. That is, the received light-sensedsignals S_(LS1)˜S_(LSM) are marked as positive light-sensed signalsS_(LS1+)˜S_(LSM+) according to the phase signal S_(P) representing“sum”. When the phase signal S_(P) represents “noise”, the storing unitsM₁˜M_(M) set the attributes of the received light-sensed signalsnegative. That is, the received light-sensed signals S_(LS1)˜S_(LSM) aremarked as negative light-sensed signals S_(LS1−)˜S_(LSM−) according tothe phase signal S_(P) representing “noise”. The distance-calculatingcircuit 140 calculates the measured distance D_(M) according to thepositive light-sensed signals S_(LS1+)˜S_(LSM+) and the negativelight-sensed signals S_(LS1−)˜S_(LSM−). The operation principle of thedistance-calculating circuit 140 calculating the measured distance D_(M)is illustrated as below.

As shown in the left part of FIG. 2, during the distance-sensing phase,the lighting/sensing controlling circuit 110 generates the lightingpulse signal S_(LD) represents “lighting” for the lighting component 120emitting the detecting light L_(ID) to the measured object MO, so thatthe measured object MO generates the reflecting light L_(RD). Meanwhile,the lighting/sensing controlling circuit 110 generates the shutter pulsesignal S_(ST) representing “turning-on” for the sensing units CS₁˜CS_(M)sensing the energy of the reflecting light L_(RD) and the backgroundlight L_(B), so that the sensing units CS₁˜CS_(M) generate thelight-sensed signals S_(LS1)˜S_(LSM) respectively. Then thelighting/sensing controlling circuit 110 outputs the reading signalS_(RE) representing “reading” for the image sensor 130 outputting thelight-sensed signals S_(LS1)˜S_(LSM) to the distance-calculating circuit140, and the lighting/sensing controlling circuit 110 generates thephase signal S_(P) representing “sum” for indicating thedistance-calculating circuit 140 that the received light-sensed signalsare the light-sensed signals of the distance-sensing phase. That is, thereceived light-sensed signals of the distance-calculating circuit 140 atthe time are the positive light-sensed signals S_(LS1+)˜S_(LSM+). It isassumed that the reflecting light L_(RD) is mainly focused on thesensing unit CS_(K) during the distance-sensing phase (as shown in FIG.2). The values of the received positive light-sensed signalsS_(LS1+)˜S_(LSM+) are shown in the right upper part of FIG. 2. Thesensing unit CS_(K) senses the background light L_(B) and the reflectinglight L_(RD) (that is, the measured object MO images on the sensing unitCS_(K)). Therefore, the light-sensed signal S_(LSK+) is equal to the sumof the energy B_(K), which is accumulated by the sensing unit CS_(K)sensing the background light L_(B), and the energy R_(K), which isaccumulated by the sensing unit CS_(K) sensing the reflecting lightL_(RD). The other sensing units only receive the background light L_(B).For example, the light-sensed signal S_(LS1+) is equal to the energy B₁,which is accumulated by the sensing unit CS₁ sensing the backgroundlight L_(B); the light-sensed signal S_(LS2+) is equal to the energy B₂,which is accumulated by the sensing unit CS₂ sensing the backgroundlight L_(B); . . . ; the light-sensed signal S_(LSM+) is equal to theenergy B_(M), which is accumulated by the sensing unit CS_(M) sensingthe background light L_(B).

As shown in the left part of FIG. 2, during the noise-sensing phase, thelighting/sensing controlling circuit 110 generates the shutter pulsesignal S_(ST) representing “turning-on” for the sensing units CS₁˜CS_(M)sensing the energy of the light focused by the lens LEN₁ so as togenerate the light-sensed signals S_(LS1)˜S_(LSM). Meanwhile, thelighting/sensing controlling circuit 110 generates the lighting pulsesignal S_(LD) represents “not-lighting”. Hence, the lighting component120 does not emit the detecting light L_(ID) to the measured object MO,so that the measured object MO does not generate the reflecting lightL_(RD). Then the lighting/sensing controlling circuit 110 outputs thereading signal S_(RE) representing “reading” for the image sensor 130outputting the light-sensed signals S_(LS1)˜S_(LSM) to thedistance-calculating circuit 140, and the lighting/sensing controllingcircuit 110 generates the phase signal S_(P) representing “noise” forindicating the distance-calculating circuit 140 that the receivedlight-sensed signals are the light-sensed signals of the noise-sensingphase at the time. That is, the received light-sensed signals of thedistance-calculating circuit 140 are the negative light-sensed signalsS_(LS1−)˜S_(LSM−). The values of the received positive light-sensedsignals S_(LS1−)˜S_(LSM−) are shown in the right lower part of FIG. 2.The pulse width of shutter pulse signal S_(ST) during thedistance-sensing phase is equal to the pulse width of shutter pulsesignal S_(ST) during the noise-sensing phase (both are equal to T_(C)).Therefore, the parts, which corresponds to the background light L_(B),of the light-sensed signals S_(LS1)˜S_(LSM) of the distance-sensingphase are equal to the parts, which corresponds to the background lightL_(B), of the light-sensed signals S_(LS1)˜S_(LSM) of the noise-sensingphase. In other words, the parts contributed by the background lightL_(B) of the positive light-sensed signals S_(LS1+)˜S_(LSM+) are equalto the parts contributed by the background light L_(B) of the negativelight-sensed signals S_(LS1)˜S_(LSM−) (both are equal to B₁˜B_(M)).

After the distance-sensing phase and the noise-sensing phase, thelighting/sensing controlling circuit 110 generates the phase signalS_(P) representing “distance-calculating”. Meanwhile, thedistance-calculating circuit 140 deducts the negative light-sensedsignals S_(LS1−)˜S_(LSM−) stored in the storing units from the positivelight-sensed signals S_(LS1+)˜SLsM₊ stored in the storing units. Thedistance-calculating circuit 140 finds out the storing units having themaximum stored value after the deduction and accordingly determines theimaging location of the reflecting light L_(RD) on the image sensor 130.More particularly, the values of the storing units M₁˜M_(M) of thedistance-calculating circuit 140 are respectively equal to the values ofthe negative light-sensed signals S_(LS1−)˜S_(LSM−) deducting from thepositive light-sensed signals S_(LS1+)˜S_(LSM+). For instance, thestoring unit M₁ stores the value of the negative light-sensed signalS_(LS1−) deducting from the positive light-sensed signal S_(LS1+). Sincethe positive light-sensed signal S_(LS1+) and the negative light-sensedsignal S_(LS−) are both equal to B₁, the stored value of the storingunit M₁ after the deduction is equal to zero. The storing unit M₂ storesthe value of the negative light-sensed signal S_(LS2−) deducting fromthe positive light-sensed signal S_(LS2+). Since the positivelight-sensed signal S_(LS2+) and the negative light-sensed signalS_(LS2−) are both equal to B₂, the stored value of the storing unit M₂after the deduction is equal to zero. Similarly, the storing unit M_(K)stores the value of the negative light-sensed signal S_(LSK−) deductingfrom the positive light-sensed signal S_(LSK+). Since the positivelight-sensed signal S_(LSK+) is equal to (R_(K)+B_(K)) and the negativelight-sensed signal S_(LSK−) is equal to B_(K), the stored value of thestoring unit M_(K) after the deduction is equal to R_(K). The storingunit M_(M) stores the value of the negative light-sensed signal S_(LSM−)deducting from the positive light-sensed signal S_(LSM+). Since thepositive light-sensed signal S_(LSM+) and the negative light-sensedsignal S_(LSM−) are both equal to B_(M), the stored value of the storingunit M_(M) after the deduction is equal to zero. In other words, amongthe storing units M₁˜M_(M), the stored value of the storing unit M_(K)is equal to R_(K), and the stored value of the other sensing units areall equal to zero. Consequently, the distance-calculating circuit 140determines the positive light-sensed signal stored in the storing unitM_(K) has the energy corresponding to the reflecting light L_(RD). Sincethe storing unit M_(K) stores the light-sensed signal generated by thesensing unit CS_(K), the distance-calculating circuit 140 determines thereflecting light L_(RD) generated by the measured object MO is mainlyfocused on the sensing unit CS_(K). In this way, thedistance-calculating circuit 140 calculates the imaging location D_(CS)of the reflecting light L_(RD) of FIG. 1 according to the sensing unitCS_(K) and the following formula:

D _(CS) =K×W _(PIX)  (1);

In addition, since, in FIG. 1, the straight light L_(F) formed betweenthe focus point O_(F1) of the lens LEN₁ and the sensing unit CS₁ isparallel to the detecting light L_(ID), the included angle θ₁ betweenthe detecting light L_(ID) and the reflecting light L_(RD) is equal tothe included angle θ₂ between the straight line L_(F) and the reflectinglight L_(RD). In other words, the relation between tan θ₁ and tan θ₂ isrepresented as the following formula:

tan θ₁ =L/D _(M)=tan θ₂ =D _(CS) /D _(F)  (2);

wherein L represents the predetermined distance between the lightingcomponent 120 and the image sensor 130 (or between the detecting lightL_(ID) and the reflecting light L_(RD)); D_(CS) represents the imaginglocation of the reflecting light L_(RD); D_(F) represent the focuslength of the lens LEN₁. The measured distance D_(M) is represented asthe following formula according to the formula (2):

D _(M)=(D _(F) ×L)/D _(CS)  (3);

as a result, the distance-calculating circuit 140 calculates the imaginglocation D_(CS) according to the formula (1), and then calculates themeasured distance D_(M) according to the predetermined distance L, thefocus length D_(F), and the formula (3).

In conclusion, in the distance-measuring device 100, during thedistance-sensing phase, the lighting/sensing controlling circuit 110controls the lighting component 120 to emit the detecting light L_(ID)to the measured object MO. The storing units M₁˜M_(M) store the positivelight-sensed signals S_(LS1+)˜S_(LSM+) generated by the sensing unitCS₁˜CS_(M) sensing the light (for instance, the reflecting light L_(RD)and the background light L_(B)) focused by the lens LEN₁. During thenoise-sensing phase, the lighting/sensing controlling circuit 110controls the lighting component 120 not to emit the detecting lightL_(ID) to the measured object MO. The storing units M₁˜M_(M) store thenegative light-sensed signals S_(LS1−)˜S_(LSM−) generated by the sensingunit CS₁˜CS_(M) sensing the light (for instance, the background lightL_(B)) focused by the lens LEN₁. Then the stored values of the storingunits M₁˜M_(M) are equal to the values of the negative light-sensedsignals S_(LS1−)˜S_(LSM−) deducting from the positive light-sensedsignals S_(LS1+)˜S_(LSM+). Thus, the stored value of the storing unitM_(K), corresponding to the sensing unit CS_(K) where the reflectinglight L_(RD) is focused, is larger than the other storing units. In thisway, the distance-calculating circuit 140 determines the reflectinglight L_(RD) is focused to the sensing unit CS_(K), and accordinglycalculates the imaging location D_(CS) of the reflecting light L_(RD).Therefore, the distance-calculating circuit 140 can calculate themeasured distance D_(M) according to the imaging location D_(CS), thefocus length D_(F) of the lens LEN₁, and the predetermined distance L.

Furthermore, in the distance-measuring device 100, the distance-sensingphase and the noise-sensing phase can repeat over and over (for example,Y times), so that the storing units M₁˜M_(M) store the positivelight-sensed signals corresponding to the Y distance-sensing phases, andstore the negative light-sensed signals corresponding to the Ynoise-sensing phases. The parts of the positive light-sensed signals,which corresponds to the background light L_(B) during eachdistance-sensing phase, are counteracted by the parts of the negativelight-sensed signals, which corresponds to the background light L_(B)during each noise-sensing phase. Hence, besides the value of the storingunit M_(K), corresponding to the sensing unit CS_(K) where thereflecting light L_(RD) is focused, is equal to (Y×R_(K)), the values ofthe other storing units are all equal to zero. In this way, even thereflecting light L_(RD) is so weak that the energy R_(K) sensed by thesensing unit CS_(K) is very small, the distance-measuring device 100still can enlarge the difference between the value of the storing unitM_(K) and the values of the other storing units by repeating thedistance-sensing phase and the noise-sensing phase for several times(that is, Y is enlarged). In this way, in spite of the weak reflectinglight L_(RD), the distance-calculating circuit 140 still can correctlydetermine the storing unit M_(K) having the maximum value, andaccordingly calculates the imaging location of the reflecting lightL_(RD).

Please refer to FIG. 3. FIG. 3 is a diagram illustrating the operationprinciple of the distance-measuring device 100 reducing the flickerphenomenon. Since the power of the general indoor light sources are fromthe AC power supply, a part of the background light L_(B) (which isreferred as the flicking light L_(F) hereinafter) flicks because of thefrequency of the AC power supply. For example, the power of the indoorfluorescent lamp is from the AC power supply. Therefore, the lightemitted by the fluorescent lamp is affected by the frequency of the ACpower supply, so that the flicker phenomenon is generated. In FIG. 3, itis assumed that the cycle of the AC power supply (or the AC cycle) isT_(F) (for example, the frequency of the AC power supply is 60 Hz, andthe AC cycle is 0.0167 s). The power P of the AC power supply varieswith time. Hence, the power of the flicking light L_(F) varies as well.However, the varying cycle of the power P of the AC power supply isequal to a half of the AC cycle (that is, T_(F)/2). For example, whenthe time is T, the power P of the AC power supply is equal to P_(T);when the time is (T+T_(F)/2), the power P of the AC power supply isstill equal to P_(T). Since the power of the flicking light isproportional to the power P of the AC power supply, the varying cycle ofthe power of the flicking light L_(F) is equal to a half of the AC cycle(that is, T_(F)/2) as well. In this way, in the distance-measuringdevice 100, the lighting/sensing controlling circuit 110 controls thetime interval between the distance-sensing phases (for example, T₁₊ andT₂₊ shown in FIG. 3) and the noise-sensing phases (for example, T¹⁻ andT²⁻ shown in FIG. 3) equal to a half of the AC cycle T_(F)/2 forreducing the effect of the flicker phenomenon. More particularly, thelighting/sensing controlling circuit 110 controls the sensing unitsCS₁˜CS_(M) sensing the flicking light L_(F) corresponding to the powerP₁ (or P₂) of the AC power supply during the distance-sensing phase T₁₊(or T₂₊), so that the parts of the positive light-sensed signals, whichcorrespond to the flicking light L_(F), are equal to F₁₁˜F_(M1) (orF₁₂˜F_(M2)). The lighting/sensing controlling circuit 110 controls thetime interval between the distance-sensing phase T₁₊ (or T₂₊) and thenoise-sensing phase T¹⁻ (or T²⁻) equal to a half of the AC cycle T_(F)/2(for example, 0.0083 s). As a result, the power of the flicking lightL_(F) sensed by the sensing units CS₁˜CS_(M) during the noise-sensingphase T¹⁻ (or T²⁻) is equal to the power of the flicking light L_(F)sensed by the sensing units CS₁˜CS_(M) during the distance-sensing phaseT₁₊ (or T₂₊). In this way, the parts, corresponding to the flickinglight L_(F), of the negative light-sensed signals generated by thesensing units CS₁˜CS_(M) during the noise-sensing phase T¹⁻ (or T²⁻) areequal to F₁₁˜F_(M1) (or F₁₂˜F_(M2)) as well. Consequently, the parts,corresponding to the flicking light L_(F), of the positive light-sensedsignals of the distance-sensing phase T₁₊ (or T₂₊) are counteracted bythe parts, corresponding to the flicking light L_(F), of the negativelight-sensed of the noise-sensing phase T¹⁻ (or T²⁻) signals. In otherwords, besides the value of the storing unit M_(K), which corresponds tothe sensing unit CS_(K) where the reflecting light L_(RD) is focused, isequal to R_(K), the values of the other storing units are all equal tozero. Hence, even the sensing units CS₁˜CS_(M) sense the flicking lightL_(F), the lighting/sensing controlling circuit 110 still can reduce theeffect of the flicker phenomenon by controlling the time intervalbetween the distance-sensing phase and the noise-sensing phase equal toa half of the AC cycle (T_(F)/2), so that the distance-calculatingcircuit 140 correctly determines the imaging location D_(CS) of thereflecting light L_(RD) and accordingly calculates the measured distanceD_(M).

Since, when the distance-measuring device 100 is assembled during thefabrication, the locations of the components of the distance-measuringdevice 100 are affected by the assembling error, the distance-measuringdevice 100 is affected by the assembling error when thedistance-measuring device 100 measures the distance. In the presentinvention, the parameter-calculating circuit 150 of thedistance-measuring device 100 is utilized for calibrating the assemblingerror of the distance-measuring device 100. The operation principle ofthe parameter-calculating circuit 150 is illustrated as below.

The parameter-calculating circuit 150 receives the known-distance signalS_(D) for obtaining a known distance D_(C1) and a known distance D_(C2),wherein the known distance D_(C1) is the distance between a calibratingobject CO₁ and the distance-measuring device 100, and the known distanceD_(C2) is the distance between a calibrating object CO₂ and thedistance-measuring device 100. By means of the method illustrated inFIG. 2, the lighting component 120 is controlled to emit the detectinglight L_(ID) to the calibrating objects CO₁ and CO₂, so that theparameter-calculating circuit 150 can obtain the imaging location of thereflecting light L_(RD) according to the light-sensed signals outputtedby the images sensor 130 and accordingly calibrates the assembling errorof the distance-measuring device 100.

First, it is assumed that the detecting light L_(ID) emitted by thelighting component 120 rotates a lighting-error angle θ_(LD) because ofthe assembling error.

Please refer to FIG. 4. FIG. 4 is a diagram illustrating a calibratingmethod of calibrating the lighting-error angle θ_(LD) of the detectinglight L_(ID) emitted by the lighting-component 120. The lighting/sensingcontrolling circuit 110 controls the lighting component 120 to emit thedetecting light L_(ID) to the calibrating object CO₁. The distancebetween the calibrating object CO₁ and the distance-measuring device 100is the known distance D_(C1). Since the detecting light L_(ID) isaffected by the assembling error of the lighting component 120, thedetecting light L_(ID) emits to the calibrating object CO₁ with alighting-error angle θ_(LD), and the reflecting light L_(RD) generatedby the calibrating object CO₁ reflecting the detecting light L_(ID) isfocused to the sensing unit CS₁. The included angle between thedetecting light L_(ID) and the reflecting light L_(RD) is θ₁₁. Theincluded angle between the straight line L_(F) and the reflecting lightL_(RD) is θ₂₁. As shown in FIG. 4, since the straight light L_(F) isparallel to the surface normal of the calibrating object CO₁,(θ₁₁-θ_(LD)) is equal to θ₂₁. That is, tan(θ₁₁-θ_(LD)) is equal to tanθ₂₁. Therefore, the following formulas are obtained:

D _(C1)=1/[1/(D _(F) ×L)×D _(CS1) +B]  (4);

B=tan θ_(LD) /L  (5);

wherein B represents the calibrating parameter for calibrating thelighting-error angle θ_(LD); D_(CS1) represents the imaging location ofthe reflecting light L_(RD). Thus, the parameter-calculating circuit 150calculates the calibrating parameter B according to the formula (4). Inthis way, the parameter-calculating circuit 150 outputs the calibratingparameter B to the distance-calculating circuit 140 through theparameter signal S_(AB), so that the distance-calculating circuit 140calibrates the formula (2) to be the following formula for calculatingthe calibrated measured distance D_(M):

D _(M)=1/[1/(D _(F) ×L)×D _(CS) +B]  (6);

as a result, even the detecting light L_(ID) emitted by the lightingcomponent 120 rotates a lighting-error angle θ_(LD) because of theassembling-error, the distance-calculating circuit 140 still cancorrectly calculate the measured distance D_(M), according to thecalibrating parameter B, the focus length of the lens LEN₁, thepredetermined distance L, and the imaging location D_(CS) of thereflecting light L_(RD) when the measured object MO is measured, bymeans of the parameter-calculating circuit 150 calculating thecalibrating parameter B capable of calibrating the lighting-error angleθ_(LD).

Please refer to FIG. 5 and FIG. 6. FIG. 5 and FIG. 6 are diagramsillustrating a calibrating method of calibrating sensing-error anglesθ_(CS1) and θ_(CS2) rotated by the image sensor 130 because of theassembling error. FIG. 5 is a top view diagram of the distance-measuringdevice 100. As shown in FIG. 5, the sensing-error angle θ_(CS1) is onthe XY plane. FIG. 6 is a side view diagram of the distance-measuringdevice 100. In addition, the sensing-error angles θ_(CS1) and θ_(CS2)are both shown in FIG. 6. The lighting/sensing controlling circuit 110controls the lighting component 120 to emit the detecting light L_(ID)to the calibrating object CO₂. The distance between the calibratingobject CO₂ and the distance-measuring device 100 is the known distanceD_(C2). In FIG. 5 and FIG. 6, it is assumed that the lighting component120 is assembled correctly (that is, the lighting-error angle θ_(LD) iszero). The detecting light L_(ID) emits to the calibrating object CO₂,and the reflecting light L_(RD) generated by the calibrating object CO₂reflecting the detecting light L_(ID) is focused to the sensing unitCS_(J). The included angle between the detecting light L_(ID) and thereflecting light L_(RD) is θ_(1J). The included angle between thestraight line L_(F) and the reflecting light L_(RD) is θ_(2J). It can beseen in FIG. 6 that D_(CSX) is a projected distance projected by theimaging location D_(CSX) of the reflecting light L_(RD), and therelation between the imaging location D_(CSX) and the projected distanceD_(CSX) is represented as the following formula:

D _(CSX) =D _(CSJ)×cos θ_(CS2)×cos θ_(CS1)  (6).

In FIG. 5, the straight line L is parallel to the detecting lightL_(ID). Consequently, the included angleθ_(2J) between the straight lineL_(F) and the reflecting light L_(RD) is equal to the included angleθ_(1J) between the detecting light L_(ID) and the reflecting lightL_(RD). That is, tan θ_(1J) is equal to tan θ_(2J). In this way, therelation between the known distance D_(C2) and the projected distanceD_(CSX) is represented as the following formula:

L/D _(C2) =D _(CSX) /D _(F)  (7);

hence, the following formulas are obtained according to the formulas (6)and (7):

D _(C2)=1/(A×D _(CSJ))  (8);

A=(cos θ_(CS2)×cos θ_(CS1))/(D _(F) ×L)  (9);

wherein A represents the calibrating parameter for calibrating thesensing-error angles θ_(CS2) and θ_(CS1). Thus, theparameter-calculating circuit 150 calculates the calibrating parameter Aaccording to the formula (8). In this way, the parameter-calculatingcircuit 150 outputs the calibrating parameter A to thedistance-calculating circuit 140 through the parameter signal S_(AB), sothat the distance-calculating circuit 140 calibrates the formula (2) tobe the following formula for calculating the calculated measureddistance D_(M):

D _(M)=1/(A×D _(CS))  (10);

it can be seen that even the image sensor 130 rotates the sensing-errorangles θ_(CS1) and θ_(CS2) because of the assembling error, thedistance-calculating circuit 140 still can correctly calculate themeasured distance D_(M), according to the calibrating parameter A, andthe imaging location D_(CS) of the reflecting light L_(RD) when themeasured object MO is measured, by means of the parameter-calculatingcircuit 150 calculating out the calibrating parameter A capable ofcalibrating the sensing-error angles θ_(CS1) and θ_(CS2).

It is assumed that the detecting light L_(ID) emitted by the lightingcomponent 120 rotates the lighting-error angle θ_(LD), and the imagesensor 130 also rotates the sensing-error angles θ_(CS1) and θ_(CS2),because of the assembling error of the distance-measuring device 100.The distance-measuring device 100 can obtain the imaging locationD_(CS1) of the reflecting light L_(RD) corresponding to the calibratingobject CO₁ and the imaging location D_(CS2) of the reflecting lightL_(RD) corresponding to the calibrating object CO₂ by the lightingcomponent 120 emitting the detecting light L_(ID) to the calibratingobjects CO₁ and CO₂, according to the illustration of FIG. 4, FIG. 5,and FIG. 6. The relations among the imaging locations D_(CS1) andD_(CS2), the known distance D_(C1) between the distance-measuring device100 and the calibrating object CO₁, the known distance D_(C2) betweenthe distance-measuring device 100 and the calibrating object CO₂, andthe calibrating parameters A and B are represented as the followingformulas:

D _(C1)=1/[A×D _(CS1) +B]  (11);

D _(C2)=1/[A×D _(CS2) +B]  (12);

the parameter-calculating circuit 150 calculates the calibratingparameter A capable of calibrating the sensing-error angles θ_(CS1) andθ_(CS2), and the calibrating parameter B capable of calibrating thelighting-error angles θ_(LD), according to the formulas (11) and (12).The parameter-calculating circuit 150 outputs the calibrating parametersA and B to the distance-calculating circuit 140 through the parametersignal S_(AB), so that the distance-calculating circuit 140 calibratesthe formula (2) to be the following formula for calculating thecalculated measured distance D_(M):

D _(M)=1/[A×D _(CS) +B]  (13);

in this way, even the detecting light L_(ID) emitted by the lightingcomponent 120 rotates the lighting-error angle θ_(LD), and the imagesensor 130 rotates the sensing-error angles θ_(CS1) and θ_(CS2) at thesame time, the distance-calculating circuit 140 still can correctlycalculate the measured distance D_(M) by the parameter-calculatingcircuit 150 calculating out the calibrating parameter A, which iscapable of calibrating the sensing-error angles θ_(CS1) and θ_(CS2), andthe calibrating parameter B, which is capable of calibrating thelighting-error angle θ_(LD).

In addition, according to the formula (13), when thedistance-calculating circuit 140 calculates the measured distance D_(M),only the calibrating parameters A and B, and the imaging location D_(CS)of the reflecting light L_(RD) when the measured object MO is measuredare required. The focus length D_(F) of the lens LEN₁ and predetermineddistance L do not have to be known. In other words, even the focuslength D_(F) of the lens LEN₁ and predetermined distance L are affectedbecause of the assembling error during the fabrication, thedistance-calculating circuit 140 still can correctly calculates themeasured distance D_(M) according to the formula (13).

Please refer to FIG. 7. FIG. 7 is a diagram illustrating the structureof an image sensor 700 according to a first embodiment of the presentinvention. As shown in FIG. 7, the M sensing units of the image sensor700 are arranged in N columns and K rows. In the image sensor 700, thehorizontal locations (that is, the location in the horizontal directionor in the direction of the X-axis shown in FIG. 7) of the sensing unitsof the same column are the same. Moreover, it is assumed that the widthsof the sensing units CS₁₁˜CS_(NK) are all equal to W_(PIX) and thehorizontal location of the left side of the sensing unit CS₁₁ isrepresented by zero. If the horizontal location of the sensing units ofone column is represented by the center of the column, then thehorizontal location of the sensing units CS₁₁˜CS_(1K) of the 1^(st)column is represented as 1/2×W_(PIX); the horizontal location of thesensing units CS₂₁˜CS_(2K) of the 2^(nd) column is represented as3/2×W_(PIX); the horizontal location of the sensing unitsCS_(N1)˜CS_(NK) of the N^(th) column is represented as[(2×N−1)×W_(PIX)]/2, and so on. Therefore, in the image sensor 700, thehorizontal locations of the sensing units of each row can be representedas {1/2×W_(PIX), 3/2×W_(PIX), . . . , [(2×N−1)×W_(PIX)]/2}, according tothe above-mentioned illustration.

Please refer to FIG. 8. FIG. 8 is a diagram illustrating the operationprinciple of detecting the imaging location D_(CS) of the reflectinglight L_(RD) by the image sensor 700. The circle shown in the upper partof FIG. 8 represents the imaging location D_(CS) of the reflecting lightL_(RD) on the image sensor 700. That is, the sensing units inside thecircle sense the energy of the reflecting light L_(RD) so as to generatethe light-sensed signals S_(LS) having the larger values than the othersensing units. For obtaining the imaging location D_(CS) of thereflecting light D_(CS), the light-sensed signals S_(LD) generated bysensing units of each column are respectively summed for obtaining theaccumulated light-sensed signals S_(ALS) for each column. For example,the accumulated light-sensed signal generated by summing thelight-sensed signals of the sensing units CS₁₁˜CS_(1K) of the 1^(st)column is S_(ALS1); the accumulated light-sensed signal generated bysumming the light-sensed signals of the sensing units CS₂₁˜CS_(2K) ofthe 2^(nd) column is S_(ALS2); the accumulated light-sensed signalgenerated by summing the light-sensed signals of the sensing unitsCS_(N1)˜CS_(NK) is of the N^(th) column S_(ALSN), and so on. Since thesensing units sensing the reflecting light L_(RD) generate thelight-sensed signals having the larger values, the sensing units nearthe imaging location D_(CS) of the reflecting light L_(RD) (that is,inside the circle) all generate the light-sensed signals having thelarger values. In other words, among the accumulated light-sensedsignals S_(ALS1)˜S_(ALSN), if the accumulated light-sensed signalS_(ALSF), which corresponds to the sensing units CS_(F1)˜CS_(FK) of theF^(th) column, has the maximum value, it represents that the imaginglocation D_(CS) of the reflecting light L_(RD) (that is, the center ofthe circle) is at the F^(th) column. In this way, the horizontaldirection of the F^(th) column is utilized for representing the imaginglocation D_(CS) of the reflecting light L_(RD). For instance, as shownin FIG. 8, the accumulated light-sensed signal S_(ALS5) corresponding tothe sensing units CS₅₁˜CS_(5K) of 5^(th) column has the maximum value.Therefore, the imaging location D_(CS) of the reflecting light L_(RD)(that is, the center of the circle) is determined at the 5^(th) column.In this way, the horizontal location of the 5^(th) column (9/2×W_(PIX))can represent the imaging location D_(CS) of the reflecting lightL_(RD).

Please refer to FIG. 9. FIG. 9 is a diagram illustrating the structureof an image sensor 900 according to another embodiment of the presentinvention. As shown in FIG. 9, the M sensing units of the image sensor900 are arranged in N columns and K rows. Comparing with the imagesensor 700, in the image sensor 900, the horizontal locations of eachsensing unit of one row is shifted by a shifting distance D_(SF), whichis assumed to be W_(PIX)/2 in FIG. 9. For example, the horizontallocations of the sensing units CS₁₁˜CS_(N1) of the 1^(st) row can berepresented as {1/2×W_(PIX), 3/2×W_(PIX), . . . , [(2×N+1)×W_(PIX)]/2};the horizontal locations of the sensing units CS₁₂˜CS_(N2) of the 2^(nd)row can be represented as {W_(PIX), 2×W_(PIX), . . . , [2×N×W_(PIX)]/2};the horizontal locations of the sensing units CS_(1K)˜CS_(NK) of theK^(th) row can be represented as {[1/2+(K−1)/2]×W_(PIX),[3/2+(K−1)/2]×W_(PIX), . . . , [(2×N−1)/2+(K−1)/2]×W_(PIX)}, and so on.

Please refer to FIG. 10. FIG. 10 is a diagram illustrating the operationprinciple of detecting the imaging location D_(CS) of the reflectinglight L_(RD) by the image sensor 900. The circle shown in the upper partof FIG. 9 represents the imaging location of the reflecting light L_(RD)on the image sensor 900. The accumulated light-sensed signals generatedaccording to the light-sensed signals of the sensing units CS₁₁˜CS_(NK)of the image sensor 900 are S_(ASL1)˜S_(ALSN). The sensing rangecorresponding to the accumulated light-sensed signals S_(ALS1) is thehorizontal locations 0˜W_(PIX)/2. Since among the sensing unitsCS₁₁˜CS_(NK), only the sensing range of the sensing unit CS₁₁ has a partin the sensing range corresponding to the accumulated light-sensedsignals S_(ALS1), the accumulated light-sensed signal S_(ALS1) is equalto the value of the light-sensed signal generated by the sensing unitCS₁₁. The sensing range corresponding to the accumulated light-sensedsignals S_(ALS2) is W_(PIX)/2˜W_(PIX). Since among the sensing unitsCS₁₁˜CS_(NK), the sensing range of the sensing unit CS₁₁ and the sensingrange of the sensing unit CS₂₁ both have a part in the sensing rangecorresponding to the accumulated light-sensed signals S_(ALS2), theaccumulated light-sensed signal S_(ALS1) is obtained by summing thelight-sensed signals generated by the sensing unit CS₁₁ and CS₂₁. Theother accumulated light-sensed signals can be obtained in similar way.Among the accumulated light-sensed signals S_(ALS1)˜S_(ALS2N), if theaccumulated light-sensed signal S_(ALSF) has the maximum value, itrepresents that the imaging location of the reflecting light L_(RD)(that is, the center of the circle) is at the sensing unitsCS_(F1)˜CS_(FK) of the F^(th) column. For instance, as shown in FIG. 10,the accumulated light-sensed signal S_(ALS10) has the maximum value.Thus, the imaging location of the reflecting light L_(RD) (that is, thecenter of the circle) is determined to be at the horizontal location ofthe accumulated light-sensed signal S_(ALS10). Since the sensing rangecorresponding to the accumulated light-sensed signal S_(ALS10) is9/2×W_(PIX)−5×W_(PIX). Consequently, the horizontal location of theaccumulated light-sensed signal S_(ALS10) is represented as19/4×W_(PIX). In this way, the horizontal location 19/4×W_(PIX)represents the imaging location D_(CS) of the reflecting light L_(RD).

Comparing with the image sensor 700, the image sensor 900 has a higherresolution. For example, when the image location D_(CS) of thereflecting light L_(RD) is detected by the image sensor 700, if thehorizontal location of the image location D_(CS) of the reflecting lightL_(RD) (the center of the circle) is actually (17/4)×W_(PIX), theaccumulated light-sensed signal S_(ALS5) has the maximum value.Therefore, the image location D_(CS) of the reflecting light L_(RD) isrepresented by the horizontal location 9/2×W_(PIX) of the 5^(th) column.However, if the horizontal location of the image location D_(CS) of thereflecting light L_(RD) (the center of the circle) changes to(19/4)×W_(PIX), the accumulated light-sensed signal S_(ALS5) still hasthe maximum value. That is, although the actual horizontal location ofthe imaging location D_(CS) of the reflecting light L_(RD) has alreadychanged from (17/4)×W_(PIX) to (19/4)×W_(PIX), the imaging locationD_(CS) of the reflecting light L_(RD) is still represented as9/2×W_(PIX) (the horizontal location of the 5^(th) column) by means ofthe image sensor 700. However, when the image location D_(CS) of thereflecting light L_(RD) is detected by the image sensor 900, if thehorizontal location of the image location D_(CS) of the reflecting lightL_(RD) (the center of the circle) is actually (17/4)×W_(PIX), theaccumulated light-sensed signal S_(ALS9) has the maximum value.Therefore, the image location D_(CS) of the reflecting light L_(RD) isrepresented by the horizontal location 17/4×W_(PIX) of the 9^(th)column. If the horizontal location of the image location D_(CS) of thereflecting light L_(RD) (the center of the circle) changes to(19/4)×W_(PIX), the accumulated light-sensed signal S_(ALS10) has themaximum value. As a result, the image location D_(CS) of the reflectinglight L_(RD) is represented by the horizontal location 19/4×W_(PIX) ofthe 10^(th) column. Consequently, the imaging location D_(CS) of thereflecting light L_(RD) are more accurately detected by the image sensor900. In conclusion, by shifting the horizontal locations of each sensingunit of the same column, the image sensor 900 has the higher resolutionthan the image sensor 700.

However, in the image sensor 900, the shifting distances between theadjacent rows of the sensing units do not have to be the same. Forexample, the shifting distance between the 1^(st) and the 2^(nd) rows ofthe sensing units is W_(PIX)/2; the shifting distance between the 2^(nd)and the 3^(rd) rows of the sensing units is W_(PIX)/4. By suchorganization, the imaging location D_(CS) of the reflecting light L_(RD)still can be detected by the method illustrated in FIG. 10.

Please refer to FIG. 11. FIG. 11 is a diagram illustrating the structureof an image sensor 1100 according to another embodiment of the presentinvention. As shown in FIG. 11, the M sensing units of the image sensor1100 are arranged in N columns and Q rows. Comparing the image sensor1100 with the image sensor 700, it can be understood that each sensingunit in the image sensor 700 is a square. However, each sensing unit inthe image sensor 1100 is a rectangle. For instance, both the width andthe height of each sensing unit of image sensor 700 are equal toW_(PIX), but, the width of each sensing unit of image sensor 1100 isW_(PIX) and the height of each sensing unit of image sensor 1100 is(W_(PIX)×K/Q), wherein Q<K. That is, the long side of each sensing unitof image sensor 1100 is in the vertical direction, and the short side ofeach sensing unit of image sensor 1100 is in the horizontal direction(the X-axis direction). In other words, each sensing unit of imagesensor 1100 has the same width as the each sensing unit of image sensor700. Although the number Q is smaller than the number K, the total areaof the sensing units of one column of the image sensor 1100 is stillequal to the total area of the sensing units of one column of the imagesensor 700. Similar to the image sensor 700, the image sensor 1100 alsoprovides M light-sensed signals generated by the M sensing units to thedistance-calculating circuit 140, so that the distance-calculatingcircuit 140 calculates the accumulated light-sensed signalsS_(ALS1)˜S_(ALSN). For example, the accumulated light-sensed signalgenerated by summing the light-sensed signals of the sensing unitsCS₁₁˜CS_(1Q) of the 1^(st) column is S_(ALS1); the accumulatedlight-sensed signal generated by summing the light-sensed signals of thesensing units CS₂₁˜CS_(2Q) of the 2^(nd) column is S_(ALS2); theaccumulated light-sensed signal generated by summing the light-sensedsignals of the sensing units CS_(N1)˜CS_(NQ) of the N^(th) column isS_(ALSN), and so on. In this way, the distance-calculating circuit 140obtains the imaging location D_(CS) of the reflecting light L_(RD)according to the accumulated light-sensed signals S_(ALS1)˜S_(ALSN) bythe method illustrated in FIG. 8, and accordingly calculates themeasured distance D_(M).

Comparing with the image sensor 700, it can be seen that in the imagesensor 1100, the side of each sensing unit in the vertical direction islonger, so that the number of sensing units of one column is reduced(that is Q<K). Therefore, the number of the accumulating times which thedistance-calculating circuit 140 generates the accumulated light-sensedsignals S_(ALS1)˜S_(ALSN), is reduced as well. Since the total area ofthe sensing units of one column of the image sensor 1100 is the same asthe total area of the sensing units of one column of the image sensor700, the received energy of the sensing units of each column sensing thelight focused by the lens LEN₁ remains unchanged. In other words, whenthe imaging location D_(CS) of the reflecting light L_(RD) is measuredby means of the image sensor 1100, the computation of thedistance-calculating circuit 140 generating the accumulated light-sensedsignals S_(ALS1)˜S_(ALSN) is reduced, and the noise-to-signal ratios ofthe accumulated light-sensed signals S_(ALS1)˜S_(ALSN) are maintained atthe same time. In addition, the short side of the sensing units of eachcolumn of the image sensor 1100 is in the horizontal direction and thewidth of each column sensing units is W_(PIX). In other words, when theimaging location D_(CS) of the reflecting light L_(RD) is measured, theimage sensor 1100 has the same resolution as the image sensor 700. Thus,comparing with the image sensor 700, it can be seen that the imagesensor 1100 reduces the computation of the distance-calculating circuit140 generating the accumulated light-sensed signals S_(ALS1)˜S_(ALSN)and maintains the resolution of the imaging location D_(CS) in thehorizontal direction (that is, the direction of the short side) and thesignal-to-noise ratios of the accumulated light-sensed signals as well.

In conclusion, the distance-measuring device provided by the presentinvention reduces the effect of the background light and the flickerphenomenon by means of removing the parts corresponding to thebackground light and the flicking light from the light-sensed signalsgenerated by the image sensor. In the image sensor of the presentinvention, the resolution is improved by shifting the sensing units ofadjacent rows. In addition, the present invention further provides acalibrating method of the distance-measuring device. The first imaginglocation corresponding to the first calibrating object and the secondimaging location corresponding to the second calibrating object arerespectively obtained by means of the lighting component emits thedetecting light to the first calibrating object with the first knowndistance and to the second calibrating object with the second knowndistance. The calibrating parameters capable of calibrating theassembling error of the distance-measuring device are calculated outaccording to the first and the second imaging location, and the firstand the second known distance. In this way, the distance-measuringdevice correctly calculates the measured distance by means of thecalibrating parameters, providing a great convenience.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention.

1. A distance-measuring device of measuring distance according tovariation of imaging location, the distance-measuring device having alighting component, a first lens, and an image sensor, the lightingcomponent utilized for emitting a detecting light to a measured objectfor the measured object generating a reflecting light, the first lensutilized for focusing a background light or the reflecting light, theimage sensor utilized for sensing an energy of a light focused by thefirst lens so as to generate M light-sensed signals, thedistance-measuring device comprising: a lighting/sensing controllingcircuit, for controlling the lighting component to emit the detectinglight and controlling the image sensor to sense the energy of the lightfocused by the first lens during a distance-sensing phase, so that theimage sensor generates M first light-sensed signals, and for controllingthe lighting component not to emit the detecting light and controllingthe image sensor to sense the energy of the light focused by the firstlens during a noise-sensing phase, so that the image sensor generates Msecond light-sensed signals; wherein M represents a positive integer;and a distance-calculating circuit, for determining an imaging locationof the reflecting light on the image sensor according to the M firstlight-sensed signals and the M second light-sensed signals, andcalculating a measured distance between the distance-measuring deviceand the measured object according to the imaging location, a focuslength of the first lens, and a predetermined distance between thelighting component and the image sensor.
 2. The distance-measuringdevice of claim 1, wherein the lighting/sensing controlling circuitcontrols the lighting component to emit the detecting light to themeasured object by generating a lighting pulse signal, so that themeasured object generates the reflecting light; the lighting/sensingcontrolling circuit controls the image sensor to sense the energy of thelight focused by the first lens by generating a shutter pulse signal, sothat the image sensor generates the M light-sensed signals; thelighting/sensing controlling circuit controls the image sensor to outputthe M light-sensed signals to the distance-calculating circuit bygenerating a reading signal; the lighting/sensing controlling circuitcontrols the distance-calculating circuit to receive the M light-sensedsignals by generating a phase signal, for the distance-calculatingcircuit determining the image location of the reflecting light on theimage sensor, and calculating the measured distance between thedistance-measuring device and the measured object according to theimaging location, the focus length of the first lens, and thepredetermined distance between the lighting component and the imagesensor.
 3. The distance-measuring device of claim 2, wherein the imagesensor comprises: M sensing units arranged in Q rows in a firstdirection and in N columns in a second direction, and respectivelyutilized for sensing the energy of the light focused by the first lensaccording to the shutter pulse signal and accordingly generating the Mlight-sensed signals, the M sensing units outputting the M light-sensedsignals according to the reading signal; wherein thedistance-calculating circuit generates N accumulated light-sensedsignals according to the M light-sensed signals and calculating themeasured distance of the measured object according to the N accumulatedlight-sensed signals; wherein the distance-calculating circuitaccumulates light-sensed signals generated by Q sensing units of anH^(th) column of the M sensing units for generating an H^(th)accumulated light-sensed signal of the N accumulated light-sensedsignals; wherein each of the M sensing units is a rectangle; a side ofeach column of the M sensing units is longer in the first direction, forreducing number of sensing units of each column of the M sensing unitsand maintaining the received energy of each column of the M sensingunits sensing the light focused by the first lens, so that accumulatingtimes that the distance-calculating circuit generates the N accumulatedlight-sensed signals is reduced and noise-to-signal ratios of the Naccumulated light-sensed signals remain unchanged; a short side of eachcolumn of the M sensing units is in the second direction, formaintaining a resolution of the image sensor in the second direction;wherein N, Q, and H all represent a positive integer respectively, and1≦H≦N.
 4. The distance-measuring device of claim 2, wherein the imagesensor comprises: M sensing units, respectively for sensing the energyof the light focused by the first lens according to the shutter pulsesignal so as to generate the M light-sensed signals, and outputting theM light-sensed signals according to the reading signal.
 5. Thedistance-measuring device of claim 4, wherein the M sensing units of theimage sensor are arranged in N columns and K rows; a location of an Xthrow of the M sensing units is shifted by a shifting distance from alocation of an adjacent (X+1)^(th) row of the M sensing units; X, N, andK all represent a positive integer respectively, and 1≦X≦(K−1).
 6. Thedistance-measuring device of claim 4, wherein the distance-calculatingcircuit comprises: a plurality of storing units, respectively forstoring the M first light-sensed signals and the M second light-sensedsignals; wherein when the phase signal represents sum, thedistance-calculating circuit marks the received M first light-sensedsignals as M positive light-sensed signals; wherein when the phasesignal represents noise, the distance-calculating circuit marks thereceived M second light-sensed signals as M negative light-sensedsignals; wherein when the phase signal represents distance-calculating,the distance-calculating circuit deducts the negative light-sensedsignals stored in the plurality of the storing units from the positivelight-sensed signals stored in the plurality of the storing units; thedistance-calculating circuit selects a storing unit having a maximumstored value so as to determine the imaging location of the reflectinglight on the image sensor, and calculates the measured distance betweenthe distance-measuring device and the measured object according to theimaging location, the focus length of the first lens, and thepredetermined distance between the lighting component and the imagesensor.
 7. The distance-measuring device of claim 6, wherein during thedistance-sensing phase, the lighting/sensing controlling circuitgenerates the lighting pulse signal and the shutter pulse signal, andthen generates the reading signal and the phase signal representing sum;during the noise-sensing phase, the lighting/sensing controlling circuitgenerates the shutter pulse signal, and then generates the readingsignal and the phase signal representing noise.
 8. Thedistance-measuring device of claim 7, wherein when the lighting pulsesignal represents lighting, the lighting component emits the detectinglight; when the shutter pulse signal represents turning-on, the Msensing units sense the energy of the light focused by the first lens;when the reading signal represents reading, the M sensing unitsrespectively output the M first light-sensed signals or the M secondlight-sensed signals.
 9. The distance-measuring device of claim 8,wherein during the distance-sensing phase, the lighting/sensingcontrolling circuit generates the lighting pulse signal representinglighting and the shutter pulse signal representing turning-on, and thengenerates the reading signal representing reading and the phase signalrepresenting sum; wherein during the distance-sensing phase, a pulsewidth of the lighting pulse signal representing lighting and a pulsewidth of the shutter pulse signal representing turning-on are both equalto a first predetermined pulse width.
 10. The distance-measuring deviceof claim 9, wherein during the noise-sensing phase, the lighting/sensingcontrolling circuit generates the shutter pulse signal representingturning-on, and then generates the reading signal representing readingand the phase signal representing noise; wherein during thenoise-sensing phase, the pulse width of the shutter pulse signalrepresenting turning-on is equal to the first predetermined pulse width.11. The distance-measuring device of claim 8, wherein during thedistance-sensing phase, a pulse width of the reading signal representingreading and a pulse width of the reading signal representing reading areboth equal to a second predetermined pulse width.
 12. Thedistance-measuring device of claim 7, wherein number of the plurality ofthe storing units is equal to M; the distance-calculating circuitdetermines the reflecting light mainly focuses to a Kth sensing unit ofthe M sensing units based on a Kth storing unit of the M storing sensingunits having a maximum stored value; wherein K represents a positiveinteger, and KM.
 13. The distance-measuring device of claim 12, whereinthe distance-calculating circuit calculates the imaging locationaccording to a following formula, based on the K^(th) storing unit ofthe M storing sensing units having the maximum stored value:D _(CS) =K×W _(PIX); wherein D_(CS) represents the imaging location,W_(PIX) represents a pixel width; wherein a width of each sensing unitof the M sensing units is equal to the pixel width.
 14. Thedistance-measuring device of claim 13, wherein when the phase signalrepresents distance-calculating, the distance-calculating circuitcalculates the measured distance according to a following formula:D _(M)=(D _(F) ×L)/D _(CS); wherein D_(M) represents the measureddistance, D_(F) represents the focus length of the first lens, Lrepresents the predetermined distance between the lighting component andthe image sensor.
 15. The distance-measuring device of claim 13, furthercomprising: a second lens, for focusing the detecting light emitting tothe measured object.
 16. The distance-measuring device of claim 1,wherein a time interval between the distance-measuring phase and thenoise-measuring phase is equal to a half of an AC cycle.
 17. Thedistance-measuring device of claim 16, wherein a half of the AC cycle isequal to 0.0083 second.
 18. The distance-measuring device of claim 1,further comprising: a parameter-calculating circuit, for receiving aknown-distance signal outputted by the lighting/sensing controllingcircuit so as to obtain a known distance between a calibrating objectand the distance-measuring device, and calculating a calibratingparameter for calibrating an assembling-error angle of thedistance-measuring device according to the known distance and a firstimaging location of the reflecting light when the calibrating object ismeasured, the parameter-calculating circuit outputting a parametersignal to the distance-calculating circuit according to the calibratingparameter; wherein the parameter-calculating circuit obtains the firstimaging location of the reflecting light when the calibrating object ismeasured according to the light-sensed signal outputted by the imagesensor.
 19. The distance-measuring device of claim 18, wherein theassembling-error angle represents a lighting-error angle rotated by thedetecting light.
 20. The distance-measuring device of claim 19, whereinthe parameter-calculating circuit calculates the calibrating parameteraccording to a following formula:D _(C1)=1/[1/(D _(F) ×L)×D _(CS1) +B]; wherein D_(C1) represents theknown distance; D_(CS1) represents the first imaging location; Brepresents the calibrating parameter; D_(F) represent the focus lengthof the first lens; L represent the predetermined distance between thelighting component and the image sensor.
 21. The distance-measuringdevice of claim 20, wherein relation between the calibrating parameterand the lighting-error angle is represented as a following formula:B=tan θ_(LD) /L; Wherein θ_(LD) represents the lighting-error angle. 22.The distance-measuring device of claim 20, wherein when thedistance-calculating circuit receives the calibrating parameter, thedistance-measuring circuit calculates the calibrated measured distanceaccording to a following formula:D _(M)=1/[1/(D _(F) ×L)×D _(CS) +B]; wherein D_(M) represents themeasured distance; D_(F) represents the focus length of the first lens;L represents the predetermined distance between the lighting componentand the image sensor; D_(CS) represents the imaging location of thereflecting light when the measured object is measured.
 23. Thedistance-measuring device of claim 18, wherein the assembling-errorangle represents a first sensing-error angle and a second sensing-errorangle of the image sensor.
 24. The distance-measuring device of claim23, wherein the parameter-calculating circuit calculates the calibratingparameter according to a following formula:D _(C2)=1/(A×D _(CSJ)); wherein D_(C2) represents the known distance;D_(CSJ) represents the first imaging location; A represents thecalibrating parameter.
 25. The distance-measuring device of claim 24,wherein relation among the calibrating parameter, the firstsensing-error angle, and the second sensing-error angle is representedas a following formula:A=(cos θ_(CS2)×cos θ_(CS1))/(D _(F) ×L); wherein θ_(CS1) represents thefirst sensing-error angle; θ_(CS2) represents the second sensing-errorangle.
 26. The distance-measuring device of claim 24, wherein when thedistance-calculating circuit receives the calibrating parameter, thedistance-measuring circuit calculates the calibrated measured distanceaccording to a following formula:D _(M)=1/(A×D _(CS)); wherein D_(M) represents the measured distance;D_(CS) represents the imaging location of the reflecting light when themeasured object is measured.
 27. A calibrating method for calibrating adistance-measuring device of measuring distance according to variationof imaging location, a lighting component of the distance-measuringdevice emitting a detecting light to a measured object, the measuredobject reflecting the detecting light to an image sensor of thedistance-measuring device for imaging at a first imaging location, thedistance-measuring device calculating a measured distance between themeasured object and the distance-measuring device according to the firstimaging location, a focus length of a first lens of thedistance-measuring device, and a predetermined distance between thelighting component and the image sensor, the calibrating methodcomprising: the lighting component of the distance-measuring deviceemitting the detecting light to a calibrating object, and thecalibrating object reflecting the detecting light to the image sensor ofthe distance-measuring device for imaging at a second imaging location;wherein a distance between the distance-measuring device and thecalibrating object is a known distance; calculating a calibratingparameter for calibrating an assembling-error angle according to theknown distance and the second imaging location; and thedistance-measuring device calculating the calculated measured distanceaccording to the calibrating parameter.
 28. The calibrating method ofclaim 27, wherein calculating the calibrating parameter for calibratingthe assembling-error angle according to the known distance, the secondimaging location comprises: calculating the calibrating parameter forcalibrating a lighting-error angle rotated by the detecting light of thelighting-component of the distance-measuring device according to theknown distance and the second imaging location.
 29. The calibratingmethod of claim 28, wherein the calibrating parameter, which is utilizedfor calibrating the lighting-error angle rotated by the detecting lightof the lighting-component of the distance-measuring device according tothe known distance and the second imaging location, is calculatedaccording to a following formula:D _(C1)=1/[1/(D _(F) ×L)×D _(CS1) +B]; wherein D_(C1) represents theknown distance; D_(CS1) represents the second imaging location; Brepresents the calibrating parameter; D_(F) represent the focus lengthof the first lens; L represent the predetermined distance between thelighting component and the image sensor.
 30. The calibrating method ofclaim 28, wherein relation between the calibrating parameter and thelighting-error angle is represented as a following formula:B=tan θ_(LD) /L; Wherein θ_(LD) represents the lighting-error angle. 31.The calibrating method of claim 29, wherein when the measured distanceis calculated according to a following formula:D _(M)=1/[1/(D _(F) ×L)×D _(CS) +B] wherein D_(M) represents themeasured distance; D_(CS) represents the first imaging location of thereflecting light when the measured object is measured.
 32. Thecalibrating method of claim 27, wherein calculating the calibratingparameter for calibrating the assembling-error angle according to theknown distance, the second imaging location comprises: calculating thecalibrating parameter for calibrating a first sensing-error angle and asecond sensing-error angle of the image sensor of the distance-measuringdevice according to the known distance and the second imaging location.33. The calibrating method of claim 32, wherein the calibratingparameter, which is utilized for calibrating the first sensing-errorangle and the second sensing-error angle of the image sensor of thedistance-measuring device according to the known distance and the secondimaging location, is calculated according to a following formula:D _(C2)=1/(A×D _(CSJ)); wherein D_(C2) represents the known distance;D_(CSJ) represents the second imaging location; A represents thecalibrating parameter.
 34. The calibrating method of claim 33, whereinrelation among the calibrating parameter, the first sensing-error angle,and the second sensing-error angle is represented as a followingformula:A=(cos θ_(CS2)×cos θ_(CS1))/(D _(F) ×L); wherein θ_(CS1) represents thefirst sensing-error angle; θ_(CS2) represents the second sensing-errorangle; D_(F) represent the focus length of the first lens; L representthe predetermined distance between the lighting component and the imagesensor.
 35. The calibrating method of claim 33, wherein the measureddistance is calculated according to a following formula:D _(M)=1/(A×D _(CS)); wherein D_(M) represents the measured distance;D_(CS) represents the first imaging location of the reflecting lightwhen the measured object is measured.